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The bronchoprotective effect of deep inspiration is flow rate dependent
Summary Background and study objective Deep inspiration (DI) protects against methacholine-induced bronchoconstriction in healthy subjects. We hypothesized that this bronchoprotective effect of DI depends upon the inspiratory flow rate. Design Prospective, controlled study. Setting Pulmonary functio...
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Published in: | Respiratory medicine 2007-07, Vol.101 (7), p.1376-1382 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Summary Background and study objective Deep inspiration (DI) protects against methacholine-induced bronchoconstriction in healthy subjects. We hypothesized that this bronchoprotective effect of DI depends upon the inspiratory flow rate. Design Prospective, controlled study. Setting Pulmonary function laboratory within a large tertiary medical center. Participants Ten healthy nonsmokers without asthma or rhinitis. Measurements First, we performed a methacholine challenge in the absence of DI to determine the concentration sufficient to reduce FEV1 by 20%. On two subsequent days, the challenge was repeated with the addition of either a fast or slow DI immediately before the threshold concentration of methacholine. We calculated the % reduction in FEV1 and FVC from baseline. Results Mean % reduction in FEV1 and FVC was significantly less with a fast DI than with no DI (20±3% vs. 34±4% for FEV1 , p =0.02; 12±3% vs. 23±3% for FVC, p =0.03); slow DIs did not significantly affect the methacholine-induced reduction in lung function. Conclusion A fast DI is bronchoprotective while a slow DI is not. Elucidating the conditions that maximize or alternatively, eliminate bronchoprotection in healthy subjects may ultimately provide insight into the pathophysiology of asthma. |
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ISSN: | 0954-6111 1532-3064 |
DOI: | 10.1016/j.rmed.2007.02.001 |